As I understand it, most (all?) nonstick coatings on pans are chemicals in this general category - some variant of fluorine compounds that hold together well. The biggest problem particularly with older ones is that they start to get less stable as heat gets higher - like it may if you leave an empty nonstick pan over a burner, where it can give off fumes that are particularly toxic to pet birds.
Avoiding those compounds likely accounts for at least some of the increased trendiness of cast iron in the past decade or two, including the increase in new "artisanal" cast iron makers like Stargazer, Finex, Butter Pat, Smithey, Field Co and probably a few others (for reviews of a bunch of those, check out Kent Rollins on Youtube). There's also quite a bit of information on improving/smoothing less expensive cast iron.
Avoiding those compounds likely accounts for at least some of the increased trendiness of cast iron in the past decade or two, including the increase in new "artisanal" cast iron makers like Stargazer, Finex, Butter Pat, Smithey, Field Co and probably a few others (for reviews of a bunch of those, check out Kent Rollins on Youtube). There's also quite a bit of information on improving/smoothing less expensive cast iron.